


The Devil Within

by KelpieChaos



Category: Shin Megami Tensei: Devil Survivor
Genre: Abel's an idiot, King of Bel!Kazuya, M/M, Post-Canon, and Naoya's a dick, and a good deal of sex, little bit of game mechanics thrown in as an excuse of a plot, mild violence, mostly just the threat of it, post overlord-warlord ending, so really what's new?, some light existential horror
Language: English
Status: Completed
Published: 2019-09-22
Updated: 2019-09-22
Packaged: 2020-07-28 00:08:13
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,012
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20054794
Author URL: https://archiveofourown.org/users/KelpieChaos/pseuds/KelpieChaos
Summary: Something was wrong.Abel didn’t know what it was, but he was absolutely, positively, one-hundred percent surethat something was very wrong.He needed… He needed to get to Naoya. His brother would fix this, he knew he would. He had to.





	The Devil Within

**Author's Note:**

  * For [morphogenesis](https://archiveofourown.org/users/morphogenesis/gifts).

> The title is technically grabbed from the song of the same name by Digital Daggers, but other than that the song and this fic don't have too terribly much in common. I do think the song does a twisted version of these two very nicely though.
> 
> Inspired by this post on tumblr: https://belfire.tumblr.com/post/94298424057/au-where-uncontracted-demons-struggle-a-great-deal

Something was wrong.

Abel didn’t know what it was, but he was absolutely, positively, one-hundred percent sure that _something was very wrong_.

He’d returned from the demon realm yesterday, and everything had been fine then. Naoya had been waiting for him in front of the server, and his friends had dragged him to Atsuro’s apartment for movies and catching up. It’d been fun just to hang and do nothing. Especially cause he’d spent the last few months endlessly fighting. God hadn’t given up easily.

But now he found himself slumped against the brick wall a block from Naoya’s apartment, barely able to breathe and shaking. Pain sparked along his skin, chased by ice deep in his bones. He grit his teeth against the sensations. Now was _not _the time to fall prey to weakness. He was the _King of Bel_, overlord of all demons, destroyer of God, for fuck’s sake. If he could just get off the street, and to Naoya, he was sure he could figure out what the hell was happening. Naoya always knew what to do.

Shoving off the wall, Abel forced himself to put one foot in front of the other until he was in front of the complex. His hands were shaking so hard it felt like he couldn’t grab his key. Dizzy, he leaned on the buzzer. The door unlocked with a sharp click, and Abel lurched forwards to grab the handle. He missed, hand seeming to pass right through the handle. Snarling, he tried again. This time he managed to connect with it. Abel shoved is way through the door and stumbled to the elevator. Distantly, he was grateful that Naoya was lazy enough that he had picked an apartment complex with an elevator. No way was he going to be able to climb three stories right now.

A cheerful _ding!_ and Abel pushed himself forwards again. It felt like the elevator wall had been the only thing holding him up, and the space between it and the corridor wall seemed like a never-ending abyss. His body was light, full of static and helium. Panic hovered somewhere in his thoughts, but even those were disorganized and far from him. What was happening? He needed… He needed to get to Naoya. His brother would fix this, he knew he would. He had to.

Abel hit the wall, hard enough the jolt rippled through him. He blinked at it. When did he get so close to it? Silver caught his eye, and, wait, this was a door, not the wall. Desperately, he tried to make out the number.

But before he could, he was falling again. It wasn’t until he was caught by something warm and soft that he realized the door had opened. He’d hit the door hard enough to get the occupant’s attention, apparently.

“Kazuya?”

That was Naoya. Oh thank fuck, that was Naoya. He curled his fingers tightly into his haori, clutching at his brother. “N-Naoya,” he gasped. “Help – I don’t – What’s happening to me?”

“Hmm.” Naoya’s hands wrapped around his elbows, not quite helping him stay steady. “It set in much earlier than I thought it would.”

...What? Abel couldn’t have heard him right. He knew this was going to happen? But – But if he knew, then he must know how to fix it!

It took more effort than he wanted to admit to push back far enough to look his brother in the face. Or to look in his general direction, as it turned out, because he couldn’t focus enough to actually see him clearly, even this close. “What… What’s happening, Naoya, please!” He swayed, buzzing filling his skull and darkness edging his vision.

“You’re running out of magnetite.”

Abel shook his head. And then regretted it, as the world kept shaking afterwards. One hand slipped, and this time he saw as it seemed to phase out in some kind of real life glitch and Naoya’s haori slid right through his closed fingers. He could hear someone in the distance panicking, and he wished they’d stop. He was quite busy with his own ordeal, and they were_ not helping_.

Naoya’s hand covered his mouth. “Hush, brother, you’ll be fine.”

Oh. He was the one panicking in the distance. He should probably stop. He grabbed his brother’s wrist and closed his eyes, trying to pull even breaths through his nose. He’d be fine. He’d be _fine_. Naoya said he would. He just needed to…needed to calm down. Calm down and listen, and Naoya would tell him how to fix this.

It helped the pain was duller now.

…That probably wasn’t a good thing actually, now that he thought about it.

Quieter now, if not calmer, Abel blinked his eyes open. He could feel tears drip down his face and puddle on Naoya’s hand, but that wasn’t important enough to relinquish either of his grips on his brother. His vision had cleared somewhat, though dark aftereffects trailed his focus.

Naoya was watching him with that amused smirk Abel was half sure was his default expression. “Better now?” He murmured, his free hand sliding to his lower back, pulling Abel closer.

At his nod, Naoya let his mouth free. Abel shivered as his larger hand settled on the side of his neck. He could feel how hard his heart was beating against Naoya’s palm. His brother’s pulse, where his hand wrapped around his wrist, was nowhere near as frantic.

“You know demons need the energy of thoughts and emotions to manifest, yes? That energy is called magnetite. It’s given off by humans when in a focused or heightened emotional state. Demons use magnetite in order to keep their form coherent in our world.” Naoya’s voice was low, steady and soothing. “When in a contract, or in consistent contact with emotional humans, demons can feed of the magnetite naturally given off by people. They can also consume humans for a larger magnetite gain. However, after a period of time without any such contact, the demons will weaken, and eventually be unable to maintain their presence in our world. Their corporeal forms disintegrate and they return to the demon world. They must be summoned again in order to reenter our world.”

Abel made a noise he hoped conveyed understanding. He didn’t know what that had to do with _him_, per se, just yet, but hopefully Naoya would get to it soon. He was getting sleepy, and the buzzing in his ears was growing louder.

“In becoming the King of Bel, you relinquished your humanity. You became a demon. Hence, your new need for magnetite.”

Oh. That…made sense. But how was he supposed to get magnetite now? He was exhausted, already fading from existence. He could only barely feel the hands on him, and his brother had been reduced to a shadowy shape in the dimness of the apartment. If he faded, would Naoya bring him back? Slowly, he felt his eyes drift shut, tears continuing to drip and trail across his cheeks. If he wasn’t so scared, this would almost be peaceful. And even now, the terror was muffled, softened by his crumbling being. It fluttered like butterfly wings against his ribcage, desperate and fragile.

“Don’t worry, brother. I’ll take care of you.” And suddenly Naoya’s lips were on his.

Faintly startled, Abel just stood there. Some small, deeply buried part of him that was still a child was jumping up and down, howling with success; he’d always wanted Naoya to focus entirely on him. But most of him was heavy and muted and confused.

And then a wave of energy hit him. Gasping, he pulled Naoya closer, possessively licking into his mouth. He felt revitalized, like someone flipped a switch in him and where he had been weeping energy like a sieve, now a waterfall of pure sugar was flooding his veins. His back hit the door, and he growled into their kiss. He would drain this human of energy if he only was given the chance.

The kiss was broken, and the human – his brother, how did he forget that, even momentarily? – near purred into his ear, “How did that feel?”

Abel sunk his teeth into Naoya’s neck, just barely shy of breaking skin. He didn’t want to rip out his brother’s throat, after all. Even if he could almost taste the magnetite pulsing through him. Admiring the already bruising skin, Abel felt himself actually purr. “More,” he demanded. Electricity was zinging through him, magnifying every nerve ending and pulling every muscle taut. If this is what it felt like from a single kiss, he wanted to see what exhausting Naoya would gain him.

From the corner of his eye, he saw his brother’s smirk widen, turn into a savage grin. “Gladly,” he promised.

The apartment blurred past him as he was dragged to the bedroom. Shoved onto the bed, Abel barely had time to suck in a breath before Naoya was on him, dragging his shirt off him and maneuvering him so his face and shoulders were pressed into the bed, ass flush against his brother’s hips. Snarling, he tried to fight his way free. Infernal instincts were screaming at him. He was King, and he would not submit that easily.

Naoya just grabbed his wrists and spread his thighs with his own. Abel could feel him laughing where his back was pressed against his chest, and threw himself against his heavy weight. But he couldn’t tear his arms free, no matter how much he tried, and Naoya’s hand on his suddenly bare hip stunned him into freezing.

“Is that it, brother? Is this the power of the mighty King of Bel? I’m surprised you managed to take down a single angel, never mind God if this is all you can do. You can’t even get yourself free from one puny human’s grasp.” His hand was just resting over Abel’s cock, hot and distracting and _not moving_.

“Cain,” Abel growled, dark promise reeking of destruction resonating in his voice. “I swear to the scraps I made of God myself, if you do not start doing _something_, I will drag you into the demon realm and you can see my power for yourself.”

His brother hummed, removing his hand to push down their pants. Light fingers just barely brushed skin as they trailed back up pale skin. “I suppose I can feed a starving beast such as you, Kazuya.” He pressed a biting kiss to the back of Abel’s neck and shoved two fingers into him.

Abel moaned, instantly grinding back. The spike of pain was consumed in a surge of lust and frantic desire to move. His instinctual urge to fight was quelled in the flood, replaced by the rush of need. He could feel how much of Naoya was focused on him, energy nearly pulsing into him with each thrust.

It wasn’t enough. He was famished, and Naoya could give him more still.

As if he could hear his thoughts, Naoya pulled his fingers out, leaving him empty and deprived. “Don’t fret so,” he scolded in response to Abel’s threat-edged grumble, “I’ll give you what you want. Patience, dear brother.” He pressed Abel’s wrists down into the bed in an attempt to convince him to keep them there, then trailed his hand down his arm and across his back, dipping into his spine to watch the shudder it caused. “You always did do that…” he muttered, taking hold of his hips. A second passed, then two, and just as Abel went to snap, to claw at his hips and drag him in himself, Naoya thrust inside him.

An electric connection slammed into place, and Abel drowned in sensation. Blistering heat and rabid energy and delirious motion and violent hunger and bright pain and dark lust and deep-seated, throbbing satisfaction. Vaguely, he felt himself slump and stretch out on the mattress, shuddering with each rough thrust and moaning louder than any succubus. He felt like he was inside Naoya’s head, like they were fusing together and he could touch every fleeting thought and emotion that passed through them. Curious and greedy, he pushed deeper, chaos surrounding him and saturating everything with cloying arousal. A cloudy mass of pulsing light drifted by, and Abel sunk his claws into it. It dissolved like so much cotton candy in water, and Abel lazily watched memories of himself bleed out around him as he licked its sweetness from his fingers. The memories floated aimlessly, then slowly coalesced back together, no longer bright but seemingly undamaged. Purring, Abel stalked the next cloud. Every thrust of their hips threw their connection awry, and he could feel the fire of his orgasm building in his body.

He just focused on draining the syrupy power from Naoya’s thoughts, glutting himself as his brother fucked him boneless.

Pleasure filled him twofold, veins pulsing with visceral ecstasy and soul singing with dreamlike satiation. His muscles trembled, twitching as he gasped and panted. His claws slowed as he savored the taste of the thoughts, needing the next bite less and less. Needing to come more and more. He sunk back into his own body, his own thoughts, let go of Naoya’s to focus on how full he felt, how he could feel the bruises on his hips forming under his brother’s fingers, how Naoya’s cock pushed into him at the perfect angle to tease at sensitive nerves. Humming, he stretched out further, pushed into the thrusts with a rolling grind. Slowly became aware of his brother’s voice, lowly swearing oaths of possession and care. Abel grinned into his shoulder, watching Naoya’s face from the corner of his eye. He might need the magnetite his brother provided, but no one owned him, not even Naoya.

Careful inch by cautious breath, Abel braced himself. He tightened around Naoya, felt him stutter and gasp in reaction. And then he exploded up, flipping his brother onto his back and settling on top of him, thighs holding him down and claws at his neck.

Naoya froze.

Abel watched him, sly smirk pulling larger as he realized exactly how trapped he was. Languid, feral eyes watched him swallow, watched as the skin _just_ touched his clawtips, red spots blooming like pinpricks. Purring still, like a great beast indulging its young, and smile showing much too many sharp teeth, Abel leaned down to murmur in his brother’s ear.

“I think you’ll find you’re mine – body, breath, and soul – much more than I’m yours.” He licked a careful line up Naoya’s jaw, tasting sweat and lust and desperation. “Though why would I stray when I could have you? There’s none that could hope to match me better than my own brother.”

He sat back, sliding himself back down onto Naoya’s cock, claws never moving from their position around his throat. Grinding down, he grinned victoriously as hands leapt to grab his hips again, tried to force him to move faster and failed. A King on his throne, Abel took his pleasure with keen disregard for his brother’s. His hand teased himself, trailing sharp nails across his chest, plucking at his nipples and laughing as Naoya’s breath hitched. Hips rolling, he dragged his hand down, leaving shallow red lines from sternum to stomach. He wrapped his hand around himself, slowly stroking his cock with the steady rocking of his hips. He could feel Naoya’s thighs shaking under his own, watched as his chest heaved and his hands shook. Felt as he got closer and closer to the edge.

Sleek satisfaction swept through him, dragging him into the blaze of release. He pumped himself through it, striping Naoya’s torso with his release, marking him with his come like a beast. Playfully, he dropped his weight fully onto his brother’s hips, small motions and teasing fluttering of muscles tearing broken noises from him. One hand still a needle-sharp threat, his other plucked his brother’s from his hip and pulled it to his mouth. Eyes lowered in facetious chagrin, he lipped at the thin skin covering the dark veins of his wrist. Gentle, he nipped at them, tiny roses of color blooming under his teeth. Naoya’s arm was loose in his grip, but that didn’t stop him from feeling as his tremors increased, as his hips jolted up into him harder. Grinning, Abel caught his brother’s gaze and slowly sunk his teeth into his wrist.

Naoya groaned as he came deep inside him. Abel let him press up into his claws, pulling back only far enough not to damage him. He licked at the indents his teeth had left and watched as Naoya shook and shuddered his way through his release, then stilled and panted, trembling from aftershocks.

Humming to himself in pleasure, Abel leaned down to press a gentle kiss just off-center of his brother’s lips, stroking soft, human fingers along the pulse racing in his neck. Mischievous glee glinting in his eyes, he murmured, dragging their lips against each other, “Thanks for the meal, big brother.”

Naoya just huffed a laugh and opened his eyes to glare half-heartedly. Met with an unrepentant grin, he sighed. “I would have appreciated some warning, Kazuya.” It wasn’t a true complaint, honest as it was.

“But then it wouldn’t be nearly as fun,” Abel pouted. “Besides, it’s not like you gave _me_ any warning that I could fade out of this world unless I consumed magnetite. The least you could do is let me get some payback.” He shuffled, pulling himself up to flop half next to and half on top of Naoya.

Lifting a hand to brush through Abel’s wild hair, Naoya hummed a considering noise. “I suppose deferring to your more primal instincts on occasion could be advantageous. At the very least, I am unconvinced that you would refrain from killing anyone else if you attempted relations with them.”

Abel shoved his face further into the warm skin against it. “See?” he mumbled, fatigue dripping from his voice. “Now shush, I’m taking a nap.”

Closing his eyes, Naoya sighed another small chuckle.

“Sleep well, brother."


End file.
